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Lesson 2.2 Basic strategy
Lesson: When to Double Down in Blackjack
In this lesson you learn when to double down. After it, you will know which hard 9 to 11 and soft 13 to 19 hands to double against each dealer up card – the dealer's face-up card – and why doubling 11 against a 6 is worth the extra bet.
What doubling down does
To double down, you place a second bet equal to your first bet. You then get exactly one more card, and your hand is finished.
- In most online games, you can double only on your first two cards.
- Your bet is now twice as big, so a win pays twice and a loss costs twice.
- You get one card only. You cannot hit again after it.
- If the chart says double but the game does not allow it, take the second move the chart gives: hit or stand.
The hand above is 11 against a dealer 6, and the strategy chart says double. More details are on the double down page.
Double hard 9, 10 and 11
A hard hand is a hand with no ace, or with an ace that must count as 1. Hard 9, 10 and 11 are the hard totals you double.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| H | D | D | D | D | H | H | H | H | H |
Hard 9: double against a dealer 3 to 6. Hit against a 2 and against 7 to ace.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| D | D | D | D | D | D | D | D | H | H |
Hard 10: double against 2 to 9. Hit against a 10 and an ace.
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| D | D | D | D | D | D | D | D | D | D |
Hard 11: double against every dealer up card, 2 to ace. The double against an ace is the chart move when the dealer hits soft 17.
A pair of 5s – two cards of the same value – is a hard 10. Double it like any other 10 – against 2 to 9 – and do not split it.
Double soft 13 to 19
A soft hand has an ace counted as 11. The ace counts as 11 unless that would bust the hand, then it counts as 1.
You double soft hands from A,2 (soft 13) to A,8 (soft 19). One card cannot bust a soft hand, because the ace can drop to 1.
| Your hand | Double against | Against other up cards |
|---|---|---|
| A,2 (soft 13) | 5–6 | Hit |
| A,3 (soft 14) | 5–6 | Hit |
| A,4 (soft 15) | 4–6 | Hit |
| A,5 (soft 16) | 4–6 | Hit |
| A,6 (soft 17) | 3–6 | Hit |
| A,7 (soft 18) | 2–6 | Stand against 7–8, hit against 9–A |
| A,8 (soft 19) | 6 | Stand |
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| Ds | Ds | Ds | Ds | Ds | S | S | H | H | H |
| 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
|---|---|---|---|---|---|---|---|---|---|
| S | S | S | S | Ds | S | S | S | S | S |
A,7 and A,8 are the soft hands you stand with when doubling is not allowed. The smaller soft hands hit instead.
A,7 against a 2 and A,8 against a 6 are doubles because the dealer hits soft 17. More on this rule is on the soft 17 page.
Learn the soft rows by the lowest dealer card you double against: A,2 and A,3 from 5, A,4 and A,5 from 4, A,6 from 3, A,7 from 2 – all up to 6. A,8 doubles against a 6 only.
Why doubling 11 against a 6 is worth it
The average result is what a move returns per first bet over a very large number of hands. A plus number means the move returns money on average.
| Move with 11 vs dealer 6 | Average result per first bet |
|---|---|
| Double | +0.674 |
| Hit | +0.337 |
Doubling has the higher average result. Any 10, J, Q or K gives you 21, and the dealer with a 6 busts about 43.9% of the time.
Dealer up card along the bottom; how often the dealer goes over 21 above each bar (6 decks, dealer hits soft 17, before any check for blackjack).
Doubling is not a sure win. You can draw a small card and lose twice your bet – the chart picks the move with the higher average result.
Practice these hands in the trainer below.
Practise: 25 hands
Only hands from this lesson. Your first answer counts.
The lesson on one card
- Doubling: add a bet equal to your first bet, then take exactly one card.
- Hard 9 vs 3–6, hard 10 vs 2–9, hard 11 vs 2–A (dealer hits soft 17).
- Soft: A,2–A,3 vs 5–6, A,4–A,5 vs 4–6, A,6 vs 3–6, A,7 vs 2–6, A,8 vs 6.
- A,7 vs 2 and A,8 vs 6 are doubles when the dealer hits soft 17.
- If doubling is not allowed, take the chart's second move: hit, but A,7 and A,8 stand.
- Doubling 11 vs 6 averages +0.674 per first bet; hitting averages +0.337.
Check yourself
1. What happens when you double down?
You add a bet equal to your first bet and get exactly one more card.
Right. Correct. After doubling, you receive one card and your hand is finished.
You add a bet and can keep hitting as many times as you like.
Not quite. Wrong. A doubled hand gets one card only, then it stands.
You split your hand into two hands.
Not quite. Wrong. That is splitting, a different move. Doubling keeps one hand with a bigger bet.
2. Why does the chart double 11 against a dealer 6 instead of hitting?
Doubling has the higher average result: +0.674 per first bet against +0.337 for hitting.
Right. Correct. Both moves return money on average, but doubling returns more per first bet.
Doubling makes sure that you win the hand.
Not quite. Wrong. You can still draw a small card and lose twice your bet.
Hitting 11 against a 6 loses money on average.
Not quite. Wrong. Hitting has a plus average result of +0.337. Doubling is simply higher.
3. You have a 4 and a 5 (hard 9) and the dealer shows a 2. What does the chart say?
Hit.
Right. Correct. Hard 9 doubles only against 3 to 6. Against a 2, you hit.
Double.
Not quite. Wrong. Hard 9 is doubled against 3 to 6, not against a 2.
Stand.
Not quite. Wrong. A total of 9 cannot bust with one card, so standing on it is never the chart move.